1. Field of the Invention
The invention relates to a cylinder head assembly comprising a holder for the attachment of units, preferably for the attachment of a high-pressure fuel injection pump onto the cylinder head of a reciprocating internal combustion engine, and a camshaft fitted to the cylinder head with at least two camshaft bearing caps.
2. Description of the Prior Art
Single-cylinder high-pressure fuel injection pumps which are attached to cylinder heads of reciprocating internal combustion engines are disclosed, for example, in DE 198 57 555. In this case, a single-cylinder high-pressure fuel injection pump is actuated by at least two additional cams which are situated at the end of a camshaft which runs in the cylinder head and is responsible for controlling the gas exchange valves. These cams also actuate a bucket tappet which in turn drives a high-pressure fuel injection pump which is connected here directly to the cylinder head with a force fit.
This above-described arrangement has a number of disadvantages. Firstly, an enlargement of the cylinder head is required because of the arrangement of the driving cams for the high-pressure fuel injection pump at the end of the existing camshaft. For package reasons this is frequently difficult to realize in particular in the case of reciprocating internal combustion engines which are installed transversely in the motor vehicle.
Secondly, the receiving bore for the bucket tappet for operating the high-pressure fuel injection pump requires additional machining steps for the cylinder head, which is in any case already very complicated to manufacture. If, for example, for a reciprocating internal combustion engine which is already mass-produced without a high-pressure fuel injection pump, a version having a high-pressure fuel injection pump is additionally to be manufactured, the component complexity for the manufacturer is increased.
The improved cylinder head assembly according to the present invention is characterized in that the holder for the attachment of units, preferably for the attachment of high-pressure fuel injection pumps, is designed in such a manner that it contains at least one camshaft bearing cap. At the same time, the existing bores which have originally been conceived only for the attachment of a camshaft bearing cap are used here for the attachment of the holder according to the invention. Therefore, in comparison with a version of a cylinder head without a high-pressure fuel injection pump, no additional machining steps on the cylinder head are necessary. However, in order to ensure that the holder is sufficiently stable, a third attachment or support point is also necessary.
In an advantageous refinement of the invention, two or more camshaft bearing caps are replaced by the holder for the attachment of high-pressure fuel injection pumps. This is a version which is particularly simple to realize and does not require any changes in terms of structure or production engineering to the cylinder head of a reciprocating internal combustion engine.
It is prior art to drive high-pressure fuel injection pumps by means of one or more cams situated on a shaft. In this case, the rotational movement of the shaft is transmitted via one or more cams to a tappet and is therefore converted into a desired linear movement. This tappet is usually designed as a bucket tappet, since bucket tappets can absorb the lateral forces arising during operation. The tappet then in turn drives the high-pressure fuel injection pump. An advantageous refinement of the present invention therefore resides in the fact that the holder for the attachment of high-pressure fuel injection pumps additionally has one or more bores for receiving at least one tappet.
In a further refinement of the invention, the abovementioned tappet is actuated by a cam of the camshaft, which cam is already present for driving the gas exchange valves. This has the advantage that, in comparison with a version without the holder according to the invention for the attachment of high-pressure fuel injection pumps, no additional components, no additional space and no additional machining steps are required.
In a further advantageous embodiment, at least one additional driving cam for the operation of a high-pressure fuel injection pump is situated on the camshaft of a reciprocating internal combustion engine. As a result, the profile configuration of the driving cam is independent of the requirements for actuating the gas exchange valves. Also, the use of two or more cams for increasing the driving frequency of the high-pressure fuel injection pump, and therefore for increasing the fuel feed power, is thus possible.
In a further advantageous refinement, the holder is dimensioned in such a manner that the space as far as a cylinder-head cover is bridged. In this version, the high-pressure injection pump can be flange-mounted onto the outside of a reciprocating internal combustion engine. This permits the high-pressure injection pump and the associated fuel and electric connections to be installed in a simple manner.
One advantage of the present invention is the improved attachment of a fuel high-pressure injection pump to a cylinder head of a reciprocating internal combustion engine in such a manner that an enlargement of the cylinder head is not necessary. A further advantage is that no additional machining of the cylinder head is required for the attachment of a fuel high-pressure injection pump. A further advantage is the simple retrofitting of a reciprocating internal combustion engine, which is already in production, with a fuel high-pressure injection pump.